Conservation Of Plant Diversity Research Articles

Accurate identification of taxon-specific molecular markers in plants based on DNA signature sequence.

Accurate identification of plants remains a significant challenge for taxonomists and is the basis for plant diversity conservation. Although DNA barcoding methods are commonly used for plant identification, these are limited by the low amplification success and low discriminative power of selected genomic regions. In this study, we developed a k-mer-based approach, the DNA signature sequence (DSS), to accurately identify plant taxon-specific markers, especially at the species level. DSS is a constant-length nucleotide sequence capable of identifying a taxon and distinguishing it from other taxa. In this study, we performed the first large-scale study of DSS markers in plants. DSS candidates of 3899 angiosperm plant species were calculated based on a chloroplast data set with 4356 assemblies. Using Sanger sequencing of PCR amplicons and high-throughput sequencing, DSSs were validated in four and 165 species, respectively. Based on this, the universality of the DSSs was over 79.38%. Several indicators influencing DSS marker identification and detection have also been evaluated, and common criteria for DSS application in plant identification have been proposed.

A Taxonomic Revision of Two Species Complexes Belonging to the Haplotricha Subsection in the Genus Onosma (Boraginaceae): A Realistic Approach to Plant Diversity

The taxonomy of O. dichroantha, O. nervosa, and their allied species is extremely controversial among authors. The delimitation of these species was extremely confusing, and closely related species were separated by weak and non-diagnostic morphological traits. A taxonomic revision of these taxa is presented here based on our fieldwork and a thorough study of herbaria specimens. The species O. dichroantha and O. sharifii are regarded as synonyms of O. setosa, and O. maculata is reduced to synonymy with O. nervosa. In addition, the typification of accepted names and relevant synonyms, detailed morphological descriptions and brief comments on the relationships between species are provided. Besides, it is accentuated that the introduction of any new species should be based on complete evidence to avoid systematic complexity. The results of this study play an important role in solving the problems of plant diversity and in the conservation of plant diversity.

Grazing during the grassland greenup period promotes plant species richness in alpine grassland in winter pastures.

Although grazing is the most common use of grassland, the ecological function of grassland far exceeds its productivity. Therefore, the protection of plant diversity is of the utmost importance and cannot be ignored. Existing research on the effect of grazing on grassland mainly focuses on grazing intensity and the type of livestock, but the consequences of the timing of the grazing on the vegetation community remains unclear. We investigated plant community characteristics of winter pastures in alpine meadow with different grazing termination times (grazing before and during the grassland greenup periods) in Maqu County, eastern QTP. The results showed that vegetation height, coverage, aboveground biomass and Graminoid biomass were lower in grassland when grazing happened during the greenup period compared to grassland where grazing was terminated before the greenup period. However, the total plant species richness and forbs richness were higher in grassland with grazing during the greenup period compared to grassland without grazing during the greenup period. Our structural equation modeling reveals a potential indirect implication for the total plant species richness and forbs richness of winter pastures mainly through a decrease in the vegetation coverage and grass biomass abundance. Our findings imply that grazing during the grassland greenup period may facilitate the maintenance of plant diversity in winter pastures. These findings have important implications for grassland ecosystem functioning and for the conservation of plant diversity.

Legal deforestation can jeopardize plant diversity conservation in an agricultural frontier in the brazilian Cerrado: a spatial explicit contribution to Santana and Simon (2022)

Legal deforestation can jeopardize plant diversity conservation in an agricultural frontier in the brazilian Cerrado: a spatial explicit contribution to Santana and Simon (2022)

Woody Species Composition, Plant Communities, and Environmental Determinants in Gennemar Dry Afromontane Forest, Southern Ethiopia.

Dry Afromontane forests in Ethiopia are vital for the conservation of plant diversity and climate change mitigation. However, these forest resources are rapidly degrading and shrinking, necessitating empirical scientific investigations to ensure their successful conservation and long-term management. As a result, this study was conducted to evaluate the composition, plant communities, and environmental determinants of woody species in the Gennemar dry Afromontane forest of southern Ethiopia. Environmental variables such as altitude, aspect, and geographical location were recorded from 46 plots of 20 × 20 m for trees and 92 subplots of 10 × 10 m for shrubs were laid along 10 transect lines. Vegetation structure, diversity, vegetation classification, importance value index (IVI) and correlation with environmental parameters were analyzed. A total of 55 woody species belonging to 51 genera and 34 families were identified. Among the species identified, Jasminum stans, Maytenus addat, and Pittosporum abyssinicum were endemic to Ethiopia. Celastraceae (with 659 individuals) was the most dominant family, followed by Cupressaceae (268 individuals) and Myrsinaceae (222 individuals). Four plant communities were identified: Syzygium guineense-Mystroxylon aethiopicum, Maytenus arbutifolia-Podocarpus falcatus, Myrsine africana-Erica arborea, and Juniperus procera-Carissa spinarum. Juniperus procera, Podocarpus falcatus, and Maytenus arbutifolia were species with the highest IVI, while Maesa lanceolata, Rhamnus prinoides, and Gnidia glauca had the lowest. The DBH class distribution shows an inverted J-shaped distribution. As DBH increases, the number of individuals decreases in the higher DBH class. The distribution of plant communities and the composition of the species depend on altitude and topographic aspects. The study found that the dry Afromontane Forest is rich in species and that it should be prioritized for conservation to protect endemic and native species. Decisive elements such as the type of species, altitude, and topographic aspects must be considered for forestry activities.

Ex situ conservation of plant diversity in Romania: A synthesis of threatened and endemic taxa

Romania hosts a relatively high species diversity, including 3,829 vascular and 979 non-vascular spontaneous plant taxa. Multiple national red lists exist, with the number of taxa assessed as threatened varying greatly between them, from 548 to 1,438, and with number of taxa assigned to a given threat category also varying between the different sources. A composite list including all taxa mentioned in at least one of the selected red listings from Romania is required in order to compensate for this lack of consensus and to assess their ex situ conservation status. In this study, we synthesized data from the national red lists and counted 1,220 spontaneous vascular plant species and 201 subspecies, of which 77 are endemic and 76 subendemic for Romania. In addition, 18 non-red-listed endemics and 14 subendemics have been added, bringing the total to 1,453 threatened and (sub)endemic plant taxa, representing almost 38% of the total native vascular flora of Romania. Despite the large network of protected areas in Romania, many taxa are still being threatened with extinction in the region mainly due to anthropogenic pressure. Several ex situ conservation measures have been employed to assure a more substantial buffer against plant extinction in the wild, supported by thorough and adequate conservation strategies and multiple means to reintroduce taxa back to their natural habitats. Consequently, our second aim was to evaluate the ex situ conservation status of these threatened and (sub)endemic plants from Romania, focussing on both conventional methods (cultivation in botanic gardens, seed banking) and biotechnological approaches (in vitro tissue culture, medium-term storage and cryostorage). Of the 1,453 taxa included in our list, 642 (44.2%) are conserved by ex situ approaches. Of these, 524 are harboured in the most important botanic gardens throughout Romania, while 156 are currently held in long-term seed banks locally or in the Millennium Seed Bank of the Royal Botanic Garden, Kew (UK). Conversely, only 64 taxa from the list are preserved at the national level through in vitro cultures, and cryopreservation protocols have been developed for only 8 taxa. Overall, more than half of the threatened and (sub)endemic vascular flora from Romania remains unprotected outside the classical in situ conservation measures. For red-listed bryophytes, only 0.6% are preserved in national ex situ collections. Moreover, some aspects related to population genetic studies and the genetic stability of ex situ conserved plants are also briefly discussed, as essential prerequisites for applied biodiversity conservation programs. Finally, considering the distribution range of targeted taxa, we included a synthesis of biotechnological approaches at both national and international level. Our study presents not only a first assessment of the ex situ conservation status of national red listed flora, but also, to our knowledge, the most comprehensive and updated overview of the rare, threatened and (sub)endemic taxa from Romania. This evaluation will provide a supporting tool for national decision- and policy-making actions for biodiversity conservation, using both in situ and ex situ approaches. We also highlight the need for an updated red list for the Romanian flora that accurately follows the IUCN assessment criteria and protocols.

Old timber plantations and secondary forests attain levels of plant diversity and structure similar to primary forests in the West African humid tropics

Considering the high rate of primary forest degradation and loss in the tropics, the ability to conserve plant diversity within alternative forest landscape components is critical to biodiversity conservation. This study compares the restoration potential of old forest plantations and secondary forests. We assessed and compared the floristics, plant species diversity, conservation value, and structure of old (42–47 years) timber plantations ofAucoumea klaineana Pierre,Cedrela odorata L.,Tarrietia utilis Sprague, andTerminalia ivorensis A. Chev. and similar-aged secondary forests with nearby primary (old-growth) forests in the moist and wet forest zones of Ghana.We established a systematic sampling set-up of ninety-three 20 m × 20 m plots in total on 11 sites, with smaller nested subplots for saplings and ground vegetation.The floristic composition of the plantation and secondary forest stands were similar to that of the primary forests, with many rare and restricted-range species shared by the three forest types. Approximately 77% and 60% of primary forest plant species also occurred in plantation and secondary forests, respectively. Species diversity, measured by the Shannon-Wiener Diversity Index (H’) and Simpson Index (S), for the primary forest (H’=3.07, S = 0.91) was not statistically different from the plantation (H’=2.85, S = 0.87) or secondary (H’=2.95, S = 0.88) forests. Overall, species richness was higher in the primary and secondary forests compared to the plantations. At the tree stratum (≥10 cm DBH), the assessed diversity indices were significantly different between the primary forest and the plantations. However, such differences did not exist among the saplings (10 cm > DBH ≥ 2 cm) and ground vegetation (<2cm DBH). The plantations and secondary forests were similar to the primary forests for all the structural characteristics assessed. However, basal area and bole volume were significantly higher in the plantations compared with secondary forests. Conservation value (using Genetic Heat Index as an indicator) was highest in one of the C. odorata plantations (W-CO).Our study demonstrates that plantation and secondary forests can develop into structurally complex and floristically diverse self-organized stands similar to primary forests. Passive conversion of plantations to more natural ecosystems is an effective and low-cost forest restoration strategy leading to diverse ecosystems with high conservation value.

Herbivory Rather than Root Competition and Environmental Factors Determines Plant Establishment in Fragmented Forests

In fragmented forests, many factors can affect plant community establishment, including abiotic factors, below-ground root competition, aboveground seed predation, and seedling herbivory. Little is known about the relative effects of biotic and abiotic factors affecting the initial stage of seedling establishment: seed gemmation and early seedling survival. Here, we carried out a root competition exclusion experiment and a herbivory (including seed predation) exclusion experiment on 11 islands in Thousand Island Lake, China, using four native woody plant species that differed in functional traits (e.g., seed mass and dominance). The dominant species on islands showed the highest seedling survival, and there was no significant linear relationship between the proportion of surviving seedlings and island area under either treatment for any species. Compared to the control and excluding root competition treatments, excluding seed predation and herbivory significantly increased seedling survival after controlling for the environmental factors. However, abiotic factors had no effect on early seedling establishment. Our results suggest that seedling regeneration of rare species in fragmented ecosystems may be limited and that seedlings may be more susceptible to predators and herbivores in fragmented ecosystems. These results have significant implications for the conservation of plant diversity in fragmented forests.

Food traditions and biodiversity conservation of the Javanese Community in Gunungkidul Karst, Yogyakarta Province, Indonesia

Local traditions manifested through foods and rituals may have contributed to the conservation of plants. In this study, we explore how the Javanese community living in the dryland Karst Gunungkidul, Yogyakarta Province, uses food traditions and rituals to conserve plant diversity and, to some extent, conserve the ecosystem. The primary method was free listing interviews with 109 respondents, which was followed by in-depth interviews with 19 people of senior members of the community, local leaders (sesepuh), and customary leaders (juru kunci). The study found that there are 43 species of 19 families used by local people to produce ten culinary varieties as the local food traditions. In addition, 29 rituals involve the use of food traditions. Some rituals such as rasulan, gumregan, and life cycle rituals reflect local ecological knowledge to support biodiversity and ecosystem conservation in the area.

PROSPEK KONSERVASI TUMBUHAN DI AREAL NILAI KONSERVASI TINGGI PERKEBUNAN KELAPA SAWIT RIAU

The purpose of the study was to analyze the prospects for plant conservation in high conservation value (HCV) oil palm plantations based on the sustainability value of plant species and population structure. The study was conducted in the HCV areas of three oil palm plantation companies and secondary forest in Riau Province. Data was collected by analyzing vegetation measuring 1.28-2.56 ha/plot in the HCV area and 3.84 ha/plot in secondary forest. Data analysis was carried out using relative density, and analysis of regeneration conditions were included in five categories (good, poor, fair, none, new). Data analysis related to the assessment of the prospect of HCV areas is carried out from the results of the analysis of the effectiveness of the HCV area and plant sustainability. The HCV area prospect assessment is grouped into three categories, namely prospective, moderately prospective, and not yet prospective. The results showed that the HCV area was not yet effective and the condition of important plant species was not sustainable. The HCV area has not been effectively assessed from the comparison of the value of the vegetation community between the HCV area and secondary forest, including low (&lt;25%). PT A's HCV area in the form of forest has a higher effectiveness value than other HCV areas and secondary forest. The results showed that the most important plant species regeneration conditions were included in the none category (57.14%). This category shows that plant species are not yet sustainable because they are only found at one growth level, namely trees. So now it can be concluded that the purpose of the existence of HCV areas in maintaining and conserving plant diversity in oil palm plantations has not been implemented properly. Key words: Conservation of plants , High conservation value, Oil palm plantations, Vegetation analysis

The importance of pollination and dispersal syndromes for the conservation of Cerrado Rupestre fragments on ironstone outcrops immersed in an agricultural landscape

Studies on pollination and seed dispersal are essential for the conservation of plant diversity. In this study, we aimed to evaluate the pollination and dispersal syndromes of five fragments of the Cerrado Rupestre immersed in an agricultural landscape to answer the following questions: (i) What is the frequency of pollination and dispersal syndromes among species and individuals?; (ii) Which are the predominant pollination and seed dispersal syndromes in this environment?. A total of 66 species, belonging to 44 genera and 29 botanical families, were evaluated. Melittophily was the most common type of pollination syndrome, observed in 54.55% of the species, followed by phalenophily (9.09%), cantharophily, ornithophily, quiropterophilly and sphingophily (all 3.03%), and psychophilly (1.51%). Generalist pollination represented 22.73% of the records. Of the 1246 individuals identified, 59.23% were melitophilous, 25.20% generalists, 5.86% phalenophilous, 3.37% quiropterophilous, 2.49% cantharophilous, 2.25% ornithophilous, 1.44% sphingophilous and 0.16% psychophilous. Regarding dispersion syndromes, zoochory was the most common type of dispersion, observed in 68.18% of the species, followed by anemochory (28.79%) and autochory (3.03%). On the other hand, the frequency among individuals differed from the values found for frequency among species. Of the 1246 individuals identified, 55.38% were anemochoric, 43.10% zoochoric, and 1.52% autochoric. Our results demonstrate the predominance of biotic syndromes in the community, especially melittophily and zoochory, contributing to a better understanding of the functionality and availability of resources in the community, as well as indispensable information for the conservation, management, and restoration of natural environments.

Plant Diversity Increased Arthropod Diversity and Crop Yield in Traditional Agroforestry Systems but Has No Effect on Herbivory

Improving agricultural production in response to the increasing food demand remains a major challenge in agroecology. The world has made significant efforts to meet this issue by developing several cultivation techniques, such as the use of chemical fertilizers and arable land conversion into agricultural land. However, most of these techniques have caused a significant loss of biodiversity and ecosystems services. Recent data suggest that biological conservation within and around agroforestry systems are potential solutions that can both reduce biodiversity loss and guarantee crop production. This logic is based on the hypothesis that increasing plant diversity in and around agricultural systems can limit the pest attack rate and increase crop yield. We tested this hypothesis using structural equation modeling on empirical data collected in agroforestry systems around the Pendjari biosphere reserve in West Africa. We measured crop diversity, crop yield, arthropod pest diversity, abundance, the rate of crop herbivory, and the diversity of plants in surrounding natural vegetation in 32 permanent plots. We estimated arthropod diversity and abundance using pitfall traps. We found a direct positive effect for plant diversity and a direct negative effect of arthropod herbivory on crop yield. The diversity of plants in surrounding natural vegetation had a direct positive effect on arthropod pest diversity but a marginal negative direct effect on the rate of crop herbivory. We found no significant direct or indirect effect for crop diversity. Our findings underline the important role of biodiversity conservation in agricultural production improvement. We suggest that the conservation of plant diversity around agroforestry systems may be an effective option to control herbivory damage. Its combination with other pest control techniques may further limit crop depredation and ensure the long-term conservation of wildlife.

An annotated checklist of the vascular plants of Taita Hills, Eastern Arc Mountain.

Taita Hills forests are an ecological island within the Tsavo plains and are the northern-most part of the Eastern Arc Mountains in southeast Kenya. They are highly fragmented forests embedded in a mosaic of human settlements and farms on the slopes and hilltops. Despite their intensive degradation, they exhibit a high degree of plant diversity and endemism, and therefore are regarded as a biodiversity hotspot. In spite of their distinct importance to the biodiversity of the region as well as supporting the livelihoods of the surrounding communities, floristic studies in these hills have been finite. Through repetitive floral expeditions, herbarium records from the East African Herbarium (EA), Global Biodiversity Information (GBIF), and the Integrated Digitized Biocollections (iDigbio) databases, as well as plant lists from literature and monographs, we provide a comprehensive checklist of 1594 taxa representing 159 families, 709 genera, 1530 species, 39 subspecies, 27 varieties, and 2 hybrids. Out of these, 75 are endemic or near-endemic, 59 are exotic, and 83 are listed as either endangered or near endangered as evaluated in the IUCN Redlist. Zehneriatuberifera G.W.Hu & Q.F.Wang, a new species to science, which has previously been described, was also discovered from the Ngangao forest fragment. Information on the habit(s), habitat(s), and altitudinal range of each taxon is provided in this study. This checklist is an updated inventory of the vascular plants of the Taita Hills. It confirms the high plant diversity of the hills and provides a clear baseline for strategic conservation and sustainable management of plant resources and diversity under the Convention on Biological Diversity (CBD).

Floristic diversity in Cold Desert regions of Uttarakhand Himalaya, India

Cold desert regions of Uttarakhand are one of the least explored remote ecosystems in the Himalaya with fragmented database. To address the issue, the task of documenting the floristic diversity of cold deserts of Uttarakhand was taken up in the present study. A total of 932 taxa (908 species, 05 subspecies and 19 varieties) belonging to 371 genera and 76 families of angiosperms and gymnosperms were recorded. In view of conservation of plant diversity, methods such as in-situ conservation, popularizing cultivation of endemic, threatened and high value medicinal plants and controlling the livestock grazing can be adopted.

Plant diversity has stronger linkage with soil fungal diversity than with bacterial diversity across grasslands of northern China

AbstractAimThe interactions between plants and soil microbes play crucial roles in modulating the function and stability of terrestrial ecosystems. However, the relationships between plant and soil microbial diversity for different taxa have remained been elusive.LocationNorthern China.Major taxaPlant and soil microbes of grassland ecosystems.Time period2018 and 2019.MethodsWe conducted a transect survey across grasslands to measure plant diversity, plant traits, and soil microbial diversity. High throughput sequencing was used to assess soil microbial diversity for bacterial 16S ribosomal RNA (16S) and fungal internal transcribed spacer (ITS) regions on an Illumina MiSeq. The random forest algorithm was used to determine the important spatial and environmental variables in predicting plant and microbial diversity, and structural equation modelling was used to examine the direct and indirect effects of climatic and edaphic variables on plant and microbial diversity.ResultsPlant diversity was positively correlated with the diversity of soil fungi, particularly for predicted arbuscular mycorrhizal fungi (AMF) and saprotrophic fungi, and they were positively related to soil nutrients and texture. However, the correlation between plant and bacterial diversity varied by phyla and functional guilds, resulting in decoupling between plant and soil bacterial diversity. Community weighted mean leaf C:N ratio indirectly decreased soil fungal diversity through a negative relationship with soil total nitrogen. Soil bacterial and fungal diversity increased with increasing functional richness of specific leaf area and stem density, respectively.Main conclusionsThese findings have contributed to unravelling the direct and indirect linkages between plant and soil fungal diversity, highlighting particularly strong linkages between plant diversity and predicted AMF and saprotrophic fungi diversity. However, we failed to detect an overall linkage between plant and soil bacterial diversity. Still, our findings suggest that integrating soil fungi into the framework of plant diversity conservation is conducive to biodiversity restoration in degraded grassland ecosystems.

Local perception of ecosystem services and their conservation in Sudanian savannas of Burkina Faso (West Africa)

ContextIn Burkina Faso, Sudanian savannas are important ecosystems for conservation of plant diversity. Due to desertification and insecurity, population migration from the North has increased human density and anthropogenic pressure on southern savannas. This study aims to investigate knowledge of local populations on ecosystem services (ES) and perception of their conservation.MethodIndividual semi-structured interviews about knowledge on ES and ecosystem conservation issues were conducted. Informants were selected according to sociocultural groups and sex in three areas of different land use intensity: the communal area of Dano (CAD), the Total Wildlife Reserve of Bontioli (TWRB) and the Game Ranch of Nazinga (GRN). The use value and vulnerability index of each plant species were determined. A cluster analysis and a principal component analysis were carried out to identify the particular knowledge of different ethnic groups.ResultsOverall, 163 plant species were cited for fifteen ES. Provisioning services were most frequently cited (100%), regulating services second most frequently (92.47%). Entire plants were exclusively used for ES with non-material benefits (protection against wind, for shading, soil fertility, erosion prevention, tourism and religion). The ten species contributing most to ES provision were Vitellaria paradoxa, Parkia biglobosa, Diospyros mespiliformis, Adansonia digitata, Lannea microcarpa, Faidherbia albida, Khaya senegalensis, Afzelia africana, Ficus sycomorus, Pterocarpus erinaceus. Seven of them were identified as highly vulnerable. Around GRN, migrants and natives shared the same knowledge, while migrants in TWRB used the ES only to a small extent due to restricted contact with the native population. Migrants and natives of GRN had more knowledge on tourism and crafts services while the natives of CAD and TWRB made use of the services that sustain the quality of the agricultural land and meet their primary needs. To reduce further degradation, different communities suggested unanimously raising awareness of the importance of biodiversity and ecosystem conservation. The most quoted motivations to preserve ecosystems were vegetation sustainability and village development.ConclusionThis study documented important local knowledge-based information to guide cultivation of local multipurpose species and initiation of communities to practice best management strategies for sustainable conservation of biodiversity.

A floristic survey across three coniferous forests of Kashmir Himalaya, India – a checklist

This study presents a checklist of the flora of three coniferous forests of the Himalayan biodiversity hotspot in Kashmir: low-level blue pine (BP), mixed coniferous (MC) and subalpine (SA) forests. The list includes altitudinal distribution and conservation status of 272 vascular plant species representing 196 genera and 64 families. Excluding neophytes (70 taxa, 62 genera, and 27 families), Magnoliophyta comprised 190 taxa, 139 genera, and 50 families; Pinophyta seven taxa, six genera, and three families; and Pteridophyta three taxa, three genera, and two families. Most speciose families from Magnoliophyta include Compositae, Apiaceae, and Rosaceae. Genera such as Artemisia, Potentilla, Viola, and Saussurea contributed the maximum number of species. In case of Pinophyta, the principal families are Pinaceae with four taxa followed by Cupressaceae (2 taxa), whereas genus Juniperus comprised two species. In Pteridophyta, Pteridaceae (2 taxa) formed the most speciose family. The herbs contributed 177 taxa, followed by tress (15 taxa), shrubs (8) and subshrubs (2). The maximum number of taxa belongs to SA (136 taxa) followed by MC (134 taxa) and BP (83 taxa) forests. The species distribution reveals 20, 30, and 46 taxa are exclusive to BP, MC, and SA forests. More than 16% of taxa are categorized in the International Union for Conservation of Nature (IUCN) Red List, and 24 taxa are endemic to the Himalayan landscape. The checklist provides a roadmap for research, protection and conservation of plant diversity, especially the threatened taxa.

Plant diversity conservation in an agricultural frontier in the Brazilian Cerrado

Plant diversity conservation in an agricultural frontier in the Brazilian Cerrado

Plant diversity increases the abundance and diversity of soil fauna: A meta-analysis

Soil fauna communities are an important component of soil biodiversity, which is key to myriad terrestrial ecosystem processes. However, despite the current alarming loss of plant diversity, it remains unclear how plant diversity affects soil fauna communities. By synthesizing 623 paired observations of plant mixtures and corresponding monocultures from 40 studies, we examined the effects of plant mixtures on soil fauna abundance and diversity. Further, we investigated the dependence of mixture effects on species richness, stand age, climate conditions, and ecosystem types. We found that, on average, the diversity of soil fauna was 10% higher in plant mixtures than the average of corresponding monocultures, while the abundance of fauna did not differ significantly between the mixtures and the average of monocultures. The mixture effects on both soil fauna abundance and diversity increased with plant species richness in mixtures, which resulted in higher abundance and diversity of soil fauna in species-rich plant mixtures than the averages of their corresponding monocultures. Moreover, the effects of plant mixtures on soil fauna abundance increased over time in diverse species mixtures. After accounting for the effects of species richness in mixtures and stand age, the effects of plant mixtures on the abundance and diversity of soil fauna were consistent across soil depths, ecosystem types, and climate conditions. Our analysis highlights the potential importance of plant diversity conservation for the maintenance of soil fauna communities.

Defining exceptional species—A conceptual framework to expand and advance ex situ conservation of plant diversity beyond conventional seed banking

The multiple, complex risks to plant species survival are increasing, and conservation strategies that include ex situ as well as in situ approaches are needed now more than ever. Seed banking (drying at c.15% relative humidity and then storing at −20 °C) is the most efficient and effective ex situ method for long-term conservation for a majority of plant species. However, some plant species are not amenable to this practice, and such species have been labeled exceptional. Critical limitations to conventional seed banking include: 1) the unavailability of sufficient seed for storage; 2) seeds that are completely intolerant of the drying process (recalcitrant); 3) fully or partially desiccation tolerant seeds that are short-lived or sensitive to storage in a conventional freezer; and 4) seeds exhibiting complex dormancies that significantly hinder post-storage germination. Here we describe species examples to illustrate the key features of these four factors of exceptionality. This definition of exceptionality will provide the foundation for identifying exceptional species and directing resources to the appropriate approaches needed for their conservation. The long-term ex situ conservation of exceptional species will require living collections, as well as technologies involving expertise in cryobiotechnology, seed biology, plant physiology, plant ecology, and horticulture, emphasizing the importance of fully integrating multi-disciplinary conservation actions underpinned by training and knowledge exchange. Given that the number of known exceptional species is anticipated to increase substantially with further research, we call for immediate, concerted, and focused international action to address the conservation needs of the world's exceptional plant species.